This invention relates to a linear motor which employs a plurality of permanent magnets to actuate an energized moving coil coupled to provide an oscillatory output.
Linear motors have been widely used when linear oscillatory outputs are desired, such as within electric shavers for example.
One known linear motor utilizes an oscillating coil for operating a double acting pump or compressor utilized within a small refrigerator such as shown in the U.S. Pat. No. 2,679,732 issued on June 1, 1954. Specifically, the U.S. Pat. No. 2,679,732 structure employs a permanent magnetic ring connected to a pair of pole shoes to form a pot-shaped magnet having an annular clearance for the oscillatory coil coupled through a piston rod to operate a pair of pistons operating within associated chambers selectively supplied with ammonia through pressure valves.
Another type of refrigerator compressor utilizing a linear motor has been disclosed in an article by J. Timmerman entitled VIBRATORS appearing in the Philips tech. Rev. 33, No. 8/9, pages 255-259 (published Jan. 25, 1974). The disclosed Philips linear motor utilizes a pair of oppositely wound movable coils providing opposing fields which interact with the magnetic field of an annular permanent magnet having axially spaced opposite poles. The disclosed Philips movable coils operate a single compressor while centrally located spiral springs are used to resonate the whole system at the mains frequency.
Another known linear motor for general application is disclosed in the U.S. Pat. No. 3,599,020 issued to Harris et al on Aug. 10, 1971 and utilizes moving coils providing fields which interact with the magnetic fields provided by a series of annularly spaced permanent magnets having circumferentially spaced poles each alternating in polarity from adjacent poles.